Fluid conservation systems, including water conservation systems, have been in use for at least the past 30 years. These systems generally fall into the following categories:                Passive full time flow rate restrictors        Manually activated one-flow rate systems        Manually activated two-flow rate systems        Timer controlled two-flow rate systems        Fluid recovery/recirculation systems        Fluid aeration or embolization systems        
Passive full time flow restrictors are the most common conservation methods employed to date. These systems provide low flow rates that are effective only if the user does not compensate for the flow rate by increasing the time use of fluid use. In practice, extended periods of fluid use, compared to nonconserving methods, can occur when the use objectives of the external object are not adequately met.
Manually activated one-flow rate systems employ one of several methods for user control of fluid flow (fully-on or fully-off). Methods disclosed in the art are typically some form of foot pressure or body weight sensing valve that is placed in series with the fluid source prior to reaching its point of fluid use as shown in U.S. Pat. No. 4,934,000.
Manually activated two-flow rate systems are known as seen in U.S. Pat. No. 5,152,465. In this system, a valve is placed in series with the fluid source prior to reaching the point of fluid use. The valve, in its inactivated state, provides a restricted flow rate. Upon manual activation, the valve opens fully to provide an unrestricted flow of fluid from the fluid source. Various methods for user activation of the valve such as but not limited to push buttons, levers, and pull chains are known.
Timer controlled two-flow rate systems are known as seen in U.S. Pat. No. 6,016,836. In this system, a timer system of highly variable sophistication is used to regulate fluid delivery and use. The most sophisticated timer-based system available uses a digital microcontroller to provide several features:                Programmable full flow time (e.g., 5, 8, 11 minutes)        Cuts to ⅓ flow rate after the time limit expires        Audible tone notifies consumer one minute prior to initiation of low flow rate mode        Fixed delay from end of time limit to reset of process (5 minutes) to prevent circumvention        
Fluid recirculation systems save fluid used at the expense of cleansing efficiency as contaminated or ‘dirty’ water is reapplied to the user. While this is acceptable for some uses, there are others for which the provision of non-pure fluids is not acceptable. Some recovery systems seek to reuse the fluid for other, non-critical related purposes such as irrigation or equipment cleaning.
Fluid aeration and embolization systems have been developed to reduce the mass flow rate of fluids used. While less fluid is used, the lower mass flow rate results may require compensation by increasing another controllable parameter, such as fluid temperature to provide equivalent heat transfer to an object compared to the non-aerated or non-embolized system. This increased temperature requirement increases the heating cost and could negatively impact one or more of the system optimization objectives.
While a variety of devices and techniques may exist for conserving and/or limiting fluid use, it is believed that no one prior to the inventor(s) has made or used an invention as described herein.
The drawings are not intended to be limiting in any way, and it is contemplated that various embodiments of the invention may be carried out in a variety of other ways, including those not necessarily depicted in the drawings. The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention, and together with the description serve to explain the principles of the invention; it being understood, however, that this invention is not limited to the precise arrangements shown.